Berlin 2015 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 13: Focus Session: Functional Semiconductor Nanowires I (organized by HL)
TT 13.10: Vortrag
Montag, 16. März 2015, 12:30–12:45, EW 201
Hard X-ray detection in a single 100 nm-diameter nanowire — •Jesper Wallentin1, Markus Osterhoff1, Robin Wilke1, Karl-Magnus Persson2, Lars-Erik Wernersson2, Michael Sprung3, and Tim Salditt1 — 1Institute for X-Ray Physics, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany — 2Department of Electrical and Information Technologies, Lund University, Lund S-221 00, Sweden — 3DESY, Notkestrasse 85, 22607 Hamburg, Germany
While hard X-rays can now be focused below 10 nm, current semiconductor-based X-ray detectors have pixel sizes of tens of micron. It is desirable to shrink the detector pixel size in order to improve the resolution in imaging, spectroscopy and crystallography, but smaller detector volumes are expected to lead to a weak electrical signal. We investigated the electrical response of a 100 nm-diameter InP nanowire exposed to a hard X-ray nanofocus. A fixed bias voltage was used, and the current was measured with a picoammeter. The conductance increased about 4 orders of magnitude under full X-ray flux. Dynamic measurements revealed very slow processes, with lifetimes at the order of seconds. Such long lifetimes, possibly related to surface states, could explain the strong X-ray induced current. As a demonstration of the potential of nanowires as X-ray detectors, we imaged the X-ray nanofocus by making a 2D raster with the device. The spatial resolution was less than 1 micron, and could be improved by making devices with the nanowire oriented along the optical axis. These results show that nanostructures can have much stronger X-ray response than expected from a simple scaling of bulk parameters.